1. Field of the Invention
The present invention relates to a mobile track renewal installation for the continuous replacement of the rails and ties of a track, which comprises a leading and a trailing work vehicle arranged for continuous advancement on a track in an operating direction, the leading vehicle bridging an intermediate renewal section where an existing track is replaced by a new track and carrying a ballast excavating and planing apparatus for removing ballast from the ballast bed and planing the remaining ballast bed, and an apparatus for laying ties on the planed ballast bed immediately behind the ballast excavating and planing apparatus, and the trailing work vehicle carrying apparatus for fastening rails to the laid ties.
2. Description of the Prior Art
This type of a mobile track renewal installation for the continuous replacement of the rails and ties of a track is disclosed in U.S. Pat. No. 3,685,456, dated Aug. 22, 1972, which comprises a track renewal train comprised of a plurality of work vehicles arranged for continuous advancement on a track in an operating direction. A leading tripartite work vehicle bridges an intermediate trackless renewal section, the central part thereof constituting a ballast cleaning machine supported on the ballast bed of the trackless renewal section on full-track undercarriages and carrying an endless ballast excavating chain, a ballast cleaning screening arrangement receiving the excavated ballast from the chain and a discharge conveyor for throwing the cleaned ballast onto the bed. The forward part of the leading work vehicle carries an apparatus for receiving the old ties and the rear part carries an apparatus for laying the new ties, suitable conveyor means being provided for transporting the old and the new ties from and to the respective apparatus. A trailing work vehicle carries apparatus for fastening the newly laid rails to the newly laid ties as well as a chute which receives and discharges cleaned ballast. A conveyor band is arranged between the ballast cleaning screening arrangement and the chute for conveying the cleaned ballast and discharging it into the cribs of the newly laid track. This mobile track renewal installation has been used with great success but the new track produced therewith is not fixed in a desired position with sufficient accuracy and stability for permanent use with high-speed trains. To achieve this result, the installation must be followed in a further operating stage by a track leveling and ballast tamping machine which properly levels and, if necessary, lines the newly laid track and then fixes it in position permanently by tamping ballast under the ties.
An advertisement in "Railway Gazette International", February 1985, pages 120/1, describes an installation for rehabilitating the subgrade of a track bed in combination with a track leveling, lining and tamping apparatus by continuously excavating an existing ballast bed and laying a new sand layer under a new ballast layer. This installation comprises a central main machine carrying a ballast excavating chain and conveyor apparatus for transporting sand and new ballast, a trailing satellite machine and a number of freight cars. The satellite machine carries a leveling-lining-tamping operating unit between its two undercarriages, which moves cyclically from tie to tie while the machine advances continuously with the main machine. Tamping is effected by vibratory and reciprocatory tamping tools which tamp ballast under the ties. While the dirty ballast is conveyed from the excavating chain to freight cars running ahead of the main machine, a gantry crane brings containers filled with sand and clean ballast to storage bins for sand and ballast. Suitable conveyor arrangements convey the sand and the ballast from the storage bins forwardly to a discharge point on the main machine rearwardly of the excavating chain to lay the sand and superposed ballast layers. Another discharge point for the ballast is provided ahead of the tamping unit. The satellite machine is integrated into the installation by the track for the gantry crane and the conveyor arrangement for conveying the ballast to the main machine. This installation has been used successfully but requires very extensive and correspondingly expensive conveyor arrangements for transporting the sand and ballast.
U.S. Pat. No. 4,479,439, dated Oct. 30, 1984, also discloses an installation for rehabilitating the subgrade of a track bed in a continuous manner. The leading work vehicle of this installation bridges a renewal section and carries an endless ballast excavating chain passing under the track and a trailing conveyor arrangement for the separate transport of sand and ballast. The rear end of the vehicle carries a sand storage bin mounted above the sand conveyor. A trailng work vehicle carries a ballast storage bin mounted above a rear end of the ballast conveyor. Tracks are mounted above the vehicle frames for guiding a gantry crane transporting containers filled with sand and ballast to the respective storage bins. A longitudinally displaceable leveling-lining-tamping unit is mounted behind the ballast storage bin. This installation is designed for the removal of the entire old ballast bed so that a sand layer may be laid on the cleared subgrade to improve drainage, whereupon a new ballast bed is laid on the sand layer and planed. The track remains unchanged and is tamped after it has been lowered onto the new ballast bed by the tamping unit on the trailing vehicle.
U.S. Pat. No. 3,628,461, dated Dec. 21, 1971, discloses a machine for working on rail fastening elements. This machine forms a part of a track renewal installation and comprises a frame supported on a track by undercarriages. A pair of operator's cabs are suspended from an underside of the machine frame and a respective apparatus for detaching and attaching rail fastening elements is longitudinally displaceably mounted on guide tracks on the machine frame underside behind each cab. This apparatus is supported on the track. In a similar flat bed car disclosed in U.S. Pat. No. 3,680,486, dated Aug. 1, 1972, a series of such operator's cabs are mounted underneath the flatbed and conveyors for rail fastening elements are arranged to convey the fastening elements from and to the cabs to enable operators therein quickly to detach and attach the fastening elements. However, it may be difficult to fasten the laid rails to the ties with this apparatus because the deposition of ballast in the cribs may make it impossible for the fastening tools to engage the fastening elements.
Austrian Pat. No. 346,891, dated Apr. 15, 1978, discloses a ballast cleaning machine with a ballast excavating chain discharging the excavated ballast into a ballast screening arrangement which, in turn, discharges the cleaned ballast into a storage bin whence the cleaned ballast is redistributed by a first conveyor arrangement and excess ballast may be moved away by a second conveyor at the rear of the machine.